Plating device

ABSTRACT

Disclosed is a plating device that has a plating tank that retains a plating fluid and carries out magnetic metal plating on a shaft shaped member immersed in the plating fluid as a negative electrode. The plating device is provided with: a plurality of shielding jigs that are fitted to the outer peripheral surface of the shaft shaped member and regulate the part of the shaft shaped member being plated; and a positive electrode provided in the vicinity of the shaft shaped member and having an output part that faces the part being plated. A center position in the axial direction of the shaft shaped member for the part being plated and a center position of the output part are aligned within a prescribed allowable value for the center positions.

TECHNICAL FIELD

The present invention relates to a plating device, for example a plating device for forming magnetostrictive films in a magnetostrictive torque sensor by a magnetic alloy plating process.

BACKGROUND ART

Vehicles are commonly equipped with, for example, electrically-powered power steering devices. An electrically-powered power steering device generates assistive torque to reduce the steering torque needed to be produced in the steering system through operation of the steering wheel by the driver. By generating assistive torque, the electrically-powered power steering device can reduce the burden on the driver. An electrically-powered power steering device has a steering torque sensor for detecting steering torque; the torque sensor for detecting torque, such as steering torque, acting on a shaft-shaped member (also called a pivot, pinion shaft, or input shaft), can be constituted, for example, by a magnetostrictive torque sensor which utilizes magnetostrictive effect by a plurality of magnetostrictive films having mutually different magnetic anisotropy.

For example, Patent Literature 1 discloses a plating device employed for forming two magnetostrictive films by plating of a plated portion of a shaft-shaped member, doing so prior to imparting having mutually different magnetic anisotropy to the films. Due to the flow of current from the positive electrode (a metal cage or metal pellets) of the plating device to an exposed portion or non-masked portion (negative electrode, plated portion) of the shaft-shaped member, metal ions (e.g. Ni ions or Fe ions) present in the plating fluid are deposited on the negative electrode side, forming a magnetic alloy plating such as a magnetostrictive film or the like.

However, because the lines of current (lines of electrical force) lead towards the plated portion (negative electrode) from the entirety of the positive electrode, the lines of current are dependent upon the pattern, such as the length, of the positive electrode, and cannot flow uniformly into the plated portion. Stated another way, depending on the type of specifications required of an electrically-powered power steering device, it may be necessary for the lines of current to flow more uniformly into the plated portion. Specifically, in the plating device disclosed in the aforementioned Patent Literature 1, it is indicated to form the shielding jig at the center to a smaller diameter than the diameter of the shielding jigs above and below, to thereby establish a uniform current density distribution over the entire surface of the plated portion. However, the inventors have found that, in actual practice, the current density distribution over the surface of the plated portion in an axial direction of a shaft-shaped member will differ depending on the location of the plated portion, in a manner dependent upon the pattern of the positive electrode, and that variability of thickness of the magnetic alloy plating may not always be kept within the allowable range, depending on the type of specifications.

PRIOR ART LITERATURE Patent Literature

Patent Literature 1: Japanese Patent Application Laid-Open

-   -   Publication No. 2008-101243

SUMMARY OF INVENTION Technical Problem

An object of the present invention is to provide a plating device whereby it is possible to more form a magnetic alloy plating to more uniform thickness.

Solution to Problem

According to a first aspect of the present invention, there is provided a plating device having a plating tank retaining a plating fluid, the device being used to carry out magnetic alloy plating of a shaft-shaped member immersed in the plating fluid, the shaft-shaped member serving as a negative electrode, wherein the plating device has a plurality of shielding jigs fitted about an outer peripheral surface of the shaft-shaped member and defining a plated portion on the shaft-shaped member, and a positive electrode disposed surrounding the shaft-shaped member, and having an output portion facing the plated portion. The center position of the plated portion and the center position of the output portion in the axial direction of the shaft-shaped member are aligned to within a predetermined tolerance relating to the center position.

In cases in which the center position of the plated portion of a shaft-shaped member and the center position of the output portion of the positive electrode are aligned in the axial direction of the shaft-shaped member, the lines of current flowing into the plated portion are symmetrical with respect to the center position of the plated portion. Consequently, despite variability of thickness of the magnetic alloy plating, by virtue of being symmetrical with respect to the center position of the plated portion, the magnetic alloy plating can be formed to more uniform thickness.

Stated another way, in cases in which the lines of current flowing into a plated portion are not symmetrical with respect to the center position of the plated portion, and moreover the thickness of the magnetic alloy plating is at its thickest or thinnest at a position furthest away from the center position of the plated portion (one end location of the plated portion), the difference between that thickness and the thickness of the magnetic alloy plating at the one end location of the plated portion will exceed the difference when the lines of current flowing into the plated portion are symmetrical with respect to the center position of the plated portion. Consequently, the variability of thickness of magnetic alloy plating observed when the lines of current flowing into the plated portion are not symmetrical with respect to the center position of the plated portion may fail to be kept within the allowable range at, for example, at one end location of the plated portion.

Accordingly, a magnetic alloy plating can be formed to more uniform thickness by aligning the center position of the plated portion of the shaft-shaped member and the center position of the output portion of the positive electrode to within an tolerance relating to center position, in order to keep the variability of thickness of magnetic alloy plating to within the allowable range throughout the entire plated portion.

In the first aspect, in preferred practice, the length of the plated portion and the length of the output portion of the positive electrode are aligned to within a predetermined tolerance relating to the length, in an axial direction of the shaft-shaped member.

In cases in which the length of the plated portion of the shaft-shaped member and the length of the output portion of the positive electrode are aligned in the axial direction of the shaft-shaped member, the lines of current flowing into the plated portion will be perpendicular to the plated portion surface. Consequently, the current density distribution will be uniform over the entire surface of the plated portion, allowing the magnetic alloy plating to be formed to more uniform thickness.

Consequently, by aligning the length of the plated portion of the shaft-shaped member and the length of the output portion of the positive electrode to within a predetermined tolerance relating to length such that variability of thickness of magnetic alloy plating is kept to within the allowable range throughout the entire plated portion, the magnetic alloy plating can be formed to more uniform thickness.

In the first aspect, in preferred practice, the plating device further has a shield disposed between the positive electrode and the shaft-shaped member.

The shield allows positive electrode output portions to be formed in portions of the positive electrode, instead of using the entire positive electrode as the output portion.

In the first aspect, in preferred practice, the pattern of the shield defines the pattern of the output portion of the positive electrode, the pattern of the shield being determined such that variability of thickness of the magnetic alloy plating is kept to within an allowable range.

Depending on the type of positive electrode, there may be instances in which the center position of the plated portion of the shaft-shaped member and the center position of the output portion of the positive electrode cannot be aligned. Or, depending on the type of positive electrode, there may be instances in which the lengths of the plated portion of the shaft-shaped member and the length of the output portion of the positive electrode cannot be aligned. Accordingly, the pattern (the center position and length) of the output portion of the positive electrode is adjusted through adjustment of the pattern of the shield, whereby the metallic alloy plating can be formed to more uniform thickness.

Moreover, depending on the type of shaft-shaped member, the pattern, such as the length, of the plated portion may differ. In such cases as well, with a single positive electrode, by adjusting the pattern of the shield, the metallic alloy plating can be formed to more uniform thickness while achieving compatibility with shaft-shaped members and plated portions of various different types.

In the first aspect, the shield is preferably of assembly type detachable from the positive electrode.

By making the shield replaceable, the metallic alloy plating can be formed to more uniform thickness, while achieving compatibility with shaft-shaped members and plated portions of various different types.

In the first aspect, in preferred practice, the plating device is further provided with a plating fluid spray nozzle having plating a fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.

Depending on the type of shaft-shaped member, the patterns, such as the center positions, of the plated portions may differ. In such cases, by replacing the plating fluid spray nozzle having plating a fluid spray orifice which faces the plated portion, the metallic alloy plating can be formed to more uniform thickness while achieving compatibility with shaft-shaped members and plated portions of various different types.

In the first aspect, in preferred practice, the center position of the plated portion and the center position of the plating fluid spray orifice are aligned to within a tolerance relating to center position, in the axial direction of the shaft-shaped member.

In cases in which the center position of the plated portion of the shaft-shaped member and the center position of the plating fluid spray orifice (the output portion of the plating fluid nozzle) are aligned in the axial direction of the shaft-shaped member, the lines of flow of the plating fluid flowing to the plated portions will be symmetrical with respect to the center positions of the plated portions. Consequently, despite variability of thickness of magnetic alloy plating, there is symmetry with respect to the center positions of the plated portions, and the metallic alloy plating can be formed to more uniform thickness. Even in cases in which the shaft-shaped member is rotated to stir the plating fluid inside the plating tank, the metallic alloy plating can be formed to more uniform composition.

In the first aspect, in preferred practice, the length of the plated portion and the length of the plating fluid spray orifice are aligned to within a tolerance relating to the length, in an axial direction of the shaft-shaped member.

In cases in which the length of the plated portion of the shaft-shaped member and the length of the plating fluid spray orifices (the output portion of the plating fluid nozzle) are aligned in the axial direction of the shaft-shaped member, the density of the metal ions flowing to the plated portion will be uniform over the entirety of the plated portions. Consequently, the metallic alloy plating can be formed to more uniform thickness. Even in cases in which the shaft-shaped member is rotated to stir the plating fluid inside the plating tank, the metallic alloy plating can be formed to more uniform composition.

It will be readily apparent to a person skilled in the art that various modifications to the aspects according to the present invention shown herein by way of examples are possible without departing from the spirit of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating a detailed example arrangement of a plating device according to the present invention;

FIG. 2 (A) illustrates a general example arrangement of the plating device of FIG. 1, and FIG. 2 (B) illustrates a detailed example arrangement of the interior of the plating tank shown in FIG. 1;

FIG. 3 (A) illustrates another general example arrangement of the plating device of FIG. 1;

FIG. 3 (B) illustrates another detailed example arrangement of the interior of the plating tank shown in FIG. 1;

FIG. 4 is a top view showing the plating tank of FIG. 1;

FIG. 5 (A) is a view showing an example external appearance of a plating fluid spray nozzle shown in FIG. 2 (B);

FIG. 5 (B) is a view showing a general example arrangement of an output portion of the plating fluid spray nozzle shown in FIG. 5 (A);

FIG. 6 (A) is a view showing an example external appearance of the plating fluid spray nozzle shown in FIG. 3 (B);

FIG. 6 (B) illustrates a modification example of a positive electrode of the plating device shown in FIG. 1;

FIG. 7 is an exploded perspective view illustrating a metal cage and a shield of FIG. 3 (B);

FIG. 8 (A) illustrates a modification example of the shield of FIG. 7;

FIG. 8 (B) illustrates a modification example of the positive electrode of FIG. 3 (B);

FIG. 9 (A) to 9 (H) respectively show descriptive diagrams in which the center position of a plated portion and the center position of an output portion are substantially aligned; and

FIG. 10 (A) to 10 (H) respectively illustrate other descriptive diagrams in which the center position of a plated portion and the center position of an output portion are substantially aligned.

DESCRIPTION OF EMBODIMENTS

Certain preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Persons skilled in the art should keep in mind that the present invention is not unduly limited to the embodiments described below.

Embodiments

FIG. 1 shows a detailed schematic example of a plating device according to the present invention, and FIG. 2 (A) shows primarily a simplified example (or enlarged view) of the scheme of the plating device (or output portions of the positive electrode) according to the present invention. In the example of FIG. 1, the plating device 1 is provided with a shield 10 m situated between the positive electrode 10 and a shaft-shaped member 5; a characterizing feature of the example in FIG. 2 (A) is that the output portion 10 s of the positive electrode 10 is defined by the shield 10 m. Stated another way, a characterizing feature of the plating device 1 of FIG. 1 is that the plating device of Patent Literature 1 is improved upon. As will be discussed below, depending on the type of positive electrode 10, the plating device 1 need not be provided with the shield 10 m, as long as the magnetic alloy plating can be formed to uniform thickness by the output portion 10 s.

In the example of FIG. 1, the plating device 1 has a plating tank 3 retaining a plating fluid 2, and is designed to carry out magnetic alloy plating on the shaft-shaped member 5 which is immersed as a negative electrode in the plating fluid 3. In the example of FIG. 2 (A), the plating device 1 is provided with a plurality of shield jigs 13, 14, 15 installed about an outside peripheral face of the shaft-shaped member 5, for defining plated portions 5 s of the shaft-shaped member 5; and with the positive electrode 10 situated surrounding the shaft-shaped member 5, and having the output portion 10 s which faces the plated portion 5 s.

Referring to FIG. 2 (A), the plurality of shield jigs 13, 14, 15 are constituted by the shield jigs 13, 15 at the upper and lower ends, and the intermediate shield jig 14 situated between the shield jigs 13, 15 at either end. The plated portion 5 s is constituted by sections of the shaft-shaped member 5 which are situated inwardly from the shield jigs 13, 15 at either end, and which are not covered by the shield jig 14. Stated another way, the plated portion 5 s is constituted by two sections of the shaft-shaped member 5 which are positioned between adjacent shield jigs among the plurality of shield jigs 13, 14, 15 (i.e., between the between adjacent shield jigs 13, 14 and between the adjacent shield jigs 14, 15). While the plated portion 5 s is constituted, for example, by two sections of the shaft-shaped member 5, the length (profile length) of the plated portion 5 s, ignoring the space between the two sections (the section covered by the shield jig 14) is equal to the distance 5 l from one end of the plated portion 5 s to the other end. In an axial direction J of the shaft-shaped member 5, the position of the one end (bottom portion) of the shaft-shaped member 5 is 0 (the origin), and the center position of the plated portion 5 s is 5 c.

Referring to FIG. 2 (A), the shield 10 m is constituted by a plurality of members, and like the plated portion 5 s, the output portion 10 s of the positive electrode 10 is constituted by sections which are defined by a plurality of members, which sections are not covered or shielded by the plurality of members. The length (profile length) of the output portion 10 s is the distance 10 l from one end of the output portion 10 s to the other end, and the center position of the output portion 10 s in the axial direction J of the shaft-shaped member 5 is 10 c. In cases in which the center position of the plated portion 5 s of the shaft-shaped member 5 and the center position 10 c of the output portion 10 s of the positive electrode 10 are aligned, the lines of current flowing into the plated portion 5 s will be symmetrical with respect to the center position of the plated portion 5 s. Consequently, variation in the thickness of the magnetic alloy plating will be symmetrical with respect to the center position of the plated portion 5 s as well, and the magnetic alloy plating can be formed to uniform thickness. However, it is not necessary for the center position 5 c and the center position 10 c of the output portion 10 s of the positive electrode 10 to be perfectly aligned, and it is sufficient for the two to be substantially aligned, as discussed below.

In the example of FIG. 2 (A), the length 5 l of the plated portion 5 s of the shaft-shaped member 5 and the length 10 l of the output portion 10 s of the positive electrode 10 in the axial direction J of the shaft-shaped member 5 are preferably substantially aligned, as discussed below. The length 5 l of the plated portion 5 s may be slightly greater than the length 10 l of the output portion 10 s, or the two may be perfectly aligned, or the length 5 l of the plated portion 5 s may be slightly shorter than the length 10 l of the output portion 10 s.

In the example of FIG. 2 (A), the center position 5 c of the plated portion 5 s of the shaft-shaped member 5 and the center position 26 c of the output portion of plating fluid spray nozzles 9 (plating fluid spray orifices 26), discussed later, are preferably substantially aligned in the axial direction J of the shaft-shaped member 5. Further, the length 61 of the plated portion 5 s of the shaft-shaped member 5 and the length 261 of the output portion of the plating fluid spray nozzles 9 are preferably substantially aligned in the axial direction J of the shaft-shaped member 5.

In the example of FIG. 1, the plating device 1 is further provided with a plating fluid regulating tank 4 for regulating the temperature and the like of the plating fluid 2, and with a rotary retainer device 6 rotatably retaining the shaft-shaped member 5 which has the plated portion 5 s. The shaft-shaped member 5 is, for example, a steering shaft comprising chrome molybdenum steel, retained in a vertical orientation at the center of the plating tank 3 by a retainer member 12 of the rotary retainer device 6. A fluid chamber 7 is situated to the outside of the bottom of the plating tank 3, and a recovery section 8 is situated to the outside in the upper portion of the plating tank; in the interior of the plating tank 3 are situated not only the positive electrode 10 and the plated portion 5 s (negative electrode), but also the plating fluid spray nozzles 9, which are made of insulating resin, for example. As discussed below, the plating fluid spray nozzles 9 are of assembly type detachable from the plating tank 3 or the fluid chamber 7, for example.

The plating fluid 2 is an alloy plating fluid containing at least two species of metal ions (e.g., Ni ions and Fe ions) in prescribed proportions, and is maintained at predetermined temperature by the plating fluid regulating tank 4. The shield jigs 13, 14, 15, which are made, for example, of insulating resin, are installed about the outside peripheral surface of the shaft-shaped member 5. The shield jigs 13, 14, 15 are of disk shape, preferably 10 mm or larger in size for example, and are separable in diametrical directions, so as to enable attachment to and detachment from the shaft-shaped member 5. The diameter of the intermediate shield jig 14 situated between the shield jigs 13, 15 at either end is preferably formed to be smaller than the diameter of the shield jigs 13, 15 at either end; the intermediate shield jig 14 may be omitted as well.

The rotary retainer device 6 is provided with a rotary shaft 18 made of metal, furnished at a vertical orientation; a lifting/lowering mechanism 19 situated in an intermediate portion of the rotary shaft 18; a bearing 20 situated in a joined portion of the rotary shaft 18 and the lifting/lowering mechanism 19; the retainer member 12 situated at one end of the rotary shaft 18; a motor 21 situated at the other end of the rotary shaft 18; and a feeder brush 23 electrically connected to the negative pole of a power supply 22 situated in proximity to the motor 21. Through up and down motion of the rotary shaft 18 by the lifting/lowering mechanism 19, the rotary retainer device 6 is able to immerse the shaft-shaped member 5 in the plating fluid 2, or withdraw the shaft-shaped member 5 up and out from the plating fluid 2. The rotary retainer device 6 is constituted such that the shaft-shaped member 5 is rotated through rotation of the rotary shaft 18 by the motor 21.

The plating fluid regulating tank 4 is provided with a stirrer 29, a temperature regulator 30, and a heater 31; the plating fluid 2 is retained inside the plating fluid regulating tank 4. Through stirring of the plating fluid 2 by the stirrer 29, for example, the Ni ion and Fe ions in the plating fluid 2 can be uniformly dispersed, as well as producing uniform temperature throughout the plating fluid 2. The temperature regulator 30 measures the temperature of the plating fluid 2, and controls the heater 31 to maintain the plating fluid 2 at the prescribed temperature.

The plating fluid 2 within the plating fluid regulating tank 4 is supplied to the fluid chamber 7 interior via a plating fluid supply line 32 through which the plating fluid regulating tank 4 interior and the fluid chamber 7 interior communicate. A pump 33, a strainer 34, and a flow meter 35 are situated midway along the plating fluid supply line 32. A controller 36 for regulating the flow rate of the plating fluid 2 is also provided, the controller 36 being connected to the pump 33 via an inverter 37. The flow rate of the plating fluid 2 passing through the plating fluid supply line 32 is measured by the flow meter 35, and the controller 36 compares the measured value thereof to a preset value, and controls the inverter 37. Through regulation of the pump flow rate of the pump 33 by the inverter 37, the flow rate of the plating fluid 2 supplied to the fluid chamber 7 interior, i.e., the flow rate of the plating fluid 2 sprayed from the plating fluid spray orifices 26 (FIG. 2B) is regulated. Dust or other foreign matter in the plating fluid 2 in the plating fluid supply line 32 is filtered out by the strainer 34.

FIG. 2 (B) shows a detailed schematic example of the interior of the plating tank 3 shown in FIG. 1. FIG. 3 (A) primarily shows another simplified example (enlarged view) of the scheme of the output portion 10 s of the positive electrode 10 of the plating device 1 shown in FIG. 1; and FIG. 3 (B) shows another detail schematic example showing the interior of the plating tank 3 of the plating device 1 shown in FIG. 1. In the example of FIG. 3, the shield jig 14 situated between the shield jigs 13, 15 at either end is omitted. Stated another way, it is acceptable for the space between the two magnetostrictive films prior to being imparted with mutually different magnetic anisotropy to be omitted, instead forming a single magnetic alloy plating in a single plated portion 5 s, and to then impart mutually different magnetic anisotropy to the single magnetic alloy plating, forming a magnetostrictive film having two functions. Furthermore, in the example of FIG. 3, the plated portion 5 s is positioned [further] towards the upper side of the plating fluid 2, as compared with the example in FIG. 2.

In the example of FIG. 2 (B) and the example of FIG. 3 (B), the plating fluid spray nozzles 9 are of assembly type detachable from the plating tank 3 via the fluid chamber 7. A flange 9 f is situated in the bottom part of the plating fluid spray nozzle 9, and the plating fluid spray nozzle 9 or the flange 9 f is fastened to the fluid chamber 7 by a plurality of bolts 9 b. The flange 9 f and the bolts 9 b are merely one example of fasteners; the fasteners could be constituted by other members or other parts.

Depending on the type of shaft-shaped member 5, the position at which the plated portion 5 s is situated on the shaft-shaped member 5 (the center position 5 c) will differ; in the example of FIG. 3 (B), the plated portion 5 s is positioned [further] towards the upper side of the plating fluid 2, as compared with the example in FIG. 2 (B). In this case as well, by replacing the plating fluid spray nozzles 9 having the plating fluid spray orifices 26 which face the plated portion 5 s, the metallic alloy plating can be formed to more uniform thickness, while achieving compatibility with shaft-shaped members 5 and plated portions 5 s of various different types. Stated another way, the plating fluid spray nozzles 9 of FIG. 2 (B) can be extended in length, positioning a plurality of the plating fluid spray orifices 26 at the top, to prepare the replacement plating fluid spray nozzles 9 of FIG. 3 (B) for example.

As discussed below, by replacing the shield 10 m, compatibility with shaft-shaped members 5 and plated portions 5 s of various different types can be achieved in the same manner as with replacement of the plating fluid spray nozzles 9.

In the example of FIG. 2 (B) and the example of FIG. 3 (B), the plating tank 3 is constituted, for example, by a cylindrical tank made of an insulating resin, or one made of metal to which an insulating coating film has been applied to the inside surface. The plating fluid 2 is supplied to the interior of the plating tank 3 from the interior of the fluid chamber 7 via the plating fluid spray nozzles 9, and overflows into the recovery section 8 from the upper edge of the plating tank 3, to be recovered in the plating fluid regulating tank 4 of FIG. 1, via a plating fluid recovery line 11 situated at the bottom of the recovery section 8.

When the power supply 22 is ON, the plating fluid 2 is sprayed from the plating fluid spray orifices 26 towards the plated portion 5 s of the rotating shaft-shaped member 5. In so doing, the plating fluid 2 is supplied to the entire surface of the plated portion 5 s, and uniform flow can be obtained over the entire surface of the plated portion 5 s. Because the shaft-shaped member 5 rotates, the concentration of Ni ions and the concentration of Fe ions in the plating fluid 2 are maintained at constant levels over the entire surface of the plated portion 5 s.

In the example of FIG. 2 (B) and the example of FIG. 3 (B), masking tape 16 is wrapped about the outside peripheral face of the shaft-shaped member 5, in a section above the upper shield jig 13 and a section below the lower shaft jig 15 (see FIG. 5 (A) and FIG. 6 (A)). The plated portion 5 s of the shaft-shaped member 5 is constituted by the section not covered by the shield jigs 13, 14, 15 or the shield jigs 13, 15, and the masking tape 16.

In the example of FIG. 2 (B) and the example of FIG. 3 (B), the positive electrode 10 is constituted by a metal cage 27 of cylindrical shape open at the top end and closed at the bottom end, and a plurality of metal pellets 28 contained within the metal cage 27. The metal cage 27 is arranged encircling the plating fluid spray nozzle 9 which is located to the inside of the inside peripheral surface thereof, and is supported by fasteners, not illustrated, in such a way as to not contact the inside peripheral surface and bottom surface of the plating tank 3. The metal cage 27 is formed, for example, of mesh comprising Ti, which does not dissolve into the plating fluid 2 when current is passed through, and is electrically connected to the positive pole of the power supply 22 (FIG. 1). The metal pellets 28, on the other hand, are pellets made, for example, of an Ni—Fe alloy which is dissolvable in the plating fluid 2, a pellet mixture of metal pellets of Ni alone and metal pellets of Fe alone, or the like. While the metal pellets 28 are employed as the positive electrode 10, spheres or any other shape would be acceptable, provided that the size is one that may be accommodated within the metal cage 27, and [large enough] to not leak out through the mesh of the metal cage 27.

Even when the Ni ions and the Fe ions in the plating fluid 2 are consumed in the course of carrying out Ni—Fe alloy plating, Ni ions and Fe ions dissolve into the plating fluid 2 from the metal pellets 28 through electrolysis, and maintain the concentration of Ni ions and the concentration of Fe ions in the plating fluid 2 at constant levels, whereby the plating fluid 2 can be easily managed. Because the constitution in one in which the metal pellets 28 are contained within the metal cage 27, the metal cage 27 can be easily supplied with the metal pellets 28, even during the plating process.

FIG. 4 shows a top view of the plating tank 3 shown in FIG. 1. FIG. 5 (A) shows an example of the exterior of the plating fluid spray nozzle 9 shown in FIG. 2 (B); and FIG. 6 (A) shows an example of the exterior of the plating fluid spray nozzle 9 shown in FIG. 3 (B). FIG. 5 (B) primarily shows a simplified schematic example of the output portion of the plating fluid spray nozzle 9 shown in FIG. 5 (A); and FIG. 6 (B) shows a modification example of the positive electrode 10 of the plating device 1 shown in FIG. 1. In the example of FIG. 4, the plating fluid spray nozzles 9 are, for example, four in number, arranged at equidistant intervals on a circle centered on the shaft-shaped member 5. The number of plating fluid spray nozzles 9 may be four or more, or one.

In the example of FIG. 6 (B), the entire positive electrode 10 faces the plated portion (negative electrode) 5 s. Stated another way, the entire positive electrode 10 of FIG. 6 (B) constitutes the output portion 10 s of the positive electrode 10 of FIG. 2 (A), the positive electrode 10 of FIG. 6 (B) being fastened such that the center position 5 c of the plated portion 5 s and the center position 10 c of the output portion 10 s are aligned. In the example of FIG. 6 (B), the plating device 1 or the plating tank 3 may be provided with the shield 10 m shown, for example, in FIG. 4.

In the example of FIG. 5 (A) and the example of FIG. 5 (B), the plurality of plating fluid spray orifices 26 are situated on the outside peripheral face of the plating fluid spray nozzle 9 so as to face the plated portion 5 s, and are arranged parallel to the axial direction of the shaft-shaped member 5. In the example of FIG. 5 (A), the plurality of plating fluid spray orifices 26 are separated into a plurality of regions (for example, an upper region and a lower region) in corresponding fashion to individual plated portions 5 s, 5 s (for example, two plated sub-portions 5 s, 5 s of the entire plated portion 5 s). The lengths 26 l 1, 26 l 2 of the individual regions (the upper region and the lower region) are preferably substantially aligned with the length 5 l 1, 5 l 2 of each one corresponding plated sub-portions 5 s. Further, the centers 26 c 1, 26 c 2 of the individual regions (the upper region and the lower region) are preferably substantially aligned with the centers 5 c 1, 5 c 2 of each one corresponding plated sub-portion 5 s. In so doing, the magnetic alloy plating can be formed to more uniform thickness, and the magnetic alloy plating can be formed to more uniform composition, even in cases in which the shaft-shaped member 5 is rotated to stir the plating fluid 2 inside the plating tank 3.

In the example of FIG. 5 (B), for example, two sub-output portions in the entire output portion 10 s of the positive electrode 10 are separated into a plurality of regions (for example, an upper region and a lower region) in corresponding fashion to the individual plated sub-portions 5 s, the lengths 10 l 1, 10 l 2 of the individual regions (the upper region and the lower region) preferably being substantially aligned with lengths 5 l, 5 l 2 of each one corresponding plated sub-portion 5 s. Further, the centers 10 c 1, 10 c 2 of the individual regions (the upper region and the lower region) are preferably substantially aligned with the centers 5 c 1, 5 c 2 of each one corresponding plated sub-portion 5 s. In so doing, the magnetic alloy plating can be formed to more uniform thickness in each of the individual plated portion 5 s, 52 (for example, the two plated sub-portions 5 s, 5 s of the entire plated portion 5 s).

FIG. 7 shows an example of an exploded perspective view of the metal cage 27 and the shield 10 m of FIG. 3 (B). In the example of FIG. 7, the shield 10 m, which is cylindrical in shape and has three openings for example, can be fastened to the inside surface (inside peripheral surface) of the metal cage 27, for example, by bolts 10 b, a frame 10 f 1, and nuts (not illustrated). The pattern of the shield 10 m defines the pattern of the output portion 10 s of the positive electrode 10, the shield 10 m preferably being of assembly type detachable from the positive electrode 10 or to the metal cage 27, for example. Stated another way, the section corresponding to the metal pellets 28 or the positive electrode 10 at the opening of the shield 10 m defines the output portion 10 s of the positive electrode 10, the shield 10 m preferably being of replaceable type. Alternatively, the metal cage 27 or the positive electrode 10 may be of replaceable type.

The metal cage 27 can be fastened to the plating tank 3 of FIG. 1 by a frame 10 f 2 and fasteners such as members or parts (not illustrated) or the like. The shield 10 m and the fasteners (the bolts 10 b, the frame 10 f 1, the frame 10 f 2, and the like) are insulators, both being constituted, for example, of an insulating substance, or the surfaces of both being coated with an insulating coating, for example.

In cases in which the metal cage 27 and the shield 10 m of FIG. 7 are applied to FIG. 2 (B), the lower side of the cylindrical shield 10 m would be furnished, for example, with three openings while closing off the opening in the section corresponding to the shield jig 14; in other words, the cylindrical shield 10 m would be furnished, for example, with [a total of] six openings.

FIG. 8 (A) shows a modification example of the shield 10 m of FIG. 7, and FIG. 8 (B) shows a modification example of the positive electrode 10 of FIG. 3 (B). In the example of FIG. 8 (A), the shield 10 m is constituted by two cylindrical members. When the shield 10 m, 10 m of FIG. 8 (A) is fastened to the metal cage 27, the output portion 10 s of the metal pellets 28 or the positive electrode 10 is defined by the space between the shield 10 m, 10 m. Stated another way, the pattern of the shield 10 m, 10 m defines the pattern of the output portion 10 s of the metal pellets 28 or the positive electrode 10.

Rather than fastening the shield 10 m, 10 m of FIG. 8 (A) to the metal cage 27, it may, for example, be fastened to six positive electrodes 10, 10, 10, 10, 10, 10 constituted by six plate-shaped members, by bolts 10 b, nuts 10 n, or the like, as in the example shown in FIG. 8 (B), for example. Stated another way, rather than having the positive electrode 10 be constituted by the metal cage 27 or the metal pellets 28, the plating device 1 may employ non-dissolving plate-shaped positive electrodes 10.

In the case of application of the shield 10 m, 10 m of FIG. 8 (A) to FIG. 2 (B), the shield 10 m would be constituted, for example, by three cylindrical members (not illustrated) including a cylindrical member in a section corresponding to the shield jig 14, with spaces between adjacent members situated at the bottom side.

FIG. 9 (A) to FIG. 9 (H) respectively show descriptive diagrams in which the center position 5 c of the plated portion 5 s (or the center positions 5 c 1, 5 c 2 of the plated sub-portions 5 s) and the center position 10 c of the output portion 10 s (or the center positions 10 c 1, 10 c 2 of the sub-output portions 10 s) are substantially aligned. FIG. 9 (C) shows the variability in film thickness of, for example, Ni—Fe alloy plating, when the center position 5 c of the plated portion 5 s and the center position 10 c of the output portion 10 s are perfectly aligned, and represents film thickness, for example, at six different positions in the plated portion 5 s of FIG. 3 (B), in the axial direction J of the shaft-shaped member 5. The ranges indicated by pairs of dotted lines in FIG. 9 (C) are allowable range relating to film thickness, and are determined according to specifications. FIG. 9 (A) and FIG. 9 (B) show the variability in film thickness when the center position 10 c of the output portion 10 s is higher than the center position 5 c of the plated portion 5 s; the center position 10 c in FIG. 9 (A) is higher than the center position 10 c in FIG. 9 (B). FIG. 9 (D) to FIG. 9 (H) show the variability in film thickness when the center position 10 c of the output portion 10 s is lower than the center position 5 c of the plated portion 5 s; the center positions 10 c in FIG. 9 (D) to FIG. 9 (H) are progressively lower in the order FIG. 9 (D) to FIG. 9 (H), with the center position 10 c in FIG. 9 (H) being the lowest.

In each of FIG. 9 (A) to FIG. 9 (F), film thickness at all six positions is maintained with in the allowable range, whereas in each of FIG. 9 (G) to FIG. 9 (H), film thickness at all six positions is not maintained within the allowable range. Consequently, [it is not necessary for] the center position 5 c of the plated portion 5 s and the center position 10 c of the output portion 10 s to be perfectly aligned (FIG. 9 (C)), it being acceptable for the center position 10 c of the output portion 10 s to be slightly higher than the center position 5 c of the plated portion 5 s (FIG. 9 (A), FIG. 9 (B)), or for the center position 10 c of the output portion 10 s to be slightly lower than the center position 5 c of the plated portion 5 s (FIG. 9 (D), FIG. 9 (E), FIG. 9 (F)), provided that the center position 5 c of the plated portion 5 s (or the center positions 5 c 1, 5 c 2) and the center position 10 c of the positive electrode 10 (or the center positions 10 c 1, 10 c 2) are aligned within the prescribed tolerance relating to center position, such that the variability of thickness of the magnetic alloy film is maintained within the acceptable range throughout the entire plated portion 5 s.

Likewise, it is acceptable for the length 5 l of the plated portion 5 s to be longer that the length 10 l of the output portion 10 s; for the two to be perfectly aligned; or for the length 5 l of the plated portion 5 s to be slightly shorter than the length 10 l of the output portion 10 s, provided that the length 5 l of the plated portion 5 s (or the lengths 5 l, 5 l 2) and length 10 l of the output portion 10 s of the positive electrode 10 (or the lengths 10 l 1, 10 l 2) are aligned within the prescribed tolerance relating to length, such that the variability of thickness of the magnetic alloy film is maintained within the acceptable range throughout the entire plated portion 5 s.

FIG. 10 (A) to FIG. 10 (H) each respectively show one more descriptive diagram in which the center position 5 c of the plated portion 5 s and the center position 10 c of the output portion 10 s are substantially aligned. FIG. 10 (C) shows variability in the iron composition or proportion of iron in, for example, Ni—Fe alloy plating, when the center position 5 c of the plated portion 5 s and the center position 10 c of the output portion 10 s are perfectly aligned. The range indicated by the pair of dotted lines in FIG. 10 (C) is an allowable range relating to iron composition, and is determined according to specifications. The center positions 10 c in FIG. 10 (A) to FIG. 10 (H) respectively correspond to the center positions in FIG. 9 (A) to FIG. 9 (H), with the center position 10 c of FIG. 10 (A) being the highest, and the center position 10 c of FIG. 10 (H) being the lowest. In each of FIG. 10 (B) to FIG. 10 (F), the iron composition at all six positions is maintained within the allowable range, whereas in each of FIG. 10 (G) to FIG. 10 (H), the iron composition at all six positions is not maintained within the allowable range.

It is preferable to take into consideration the iron composition, not just the film thickness, whereby the center position 5 c of the plated portion 5 s (or the center positions 5 c 1, 5 c 2) and the center position 10 c of the positive electrode 10 (or the center positions 10 c 1, 10 c 2) can be aligned within the prescribed tolerance relating to center position (FIG. 10 (B) to FIG. 10 (F), FIG. 9 (B) to FIG. 9 (F)), so that variability of each component of the magnetic alloy plating is maintained within an allowable range throughout the entire plated portion 5 s. Likewise, it is preferable to take into consideration the iron composition, not just the film thickness, whereby the length 5 l of the plated portion 5 s (or the lengths 5 l, 5 l 2) and length 10 l of the output portion 10 s of the positive electrode 10 (or the lengths 10 l 1, 10 l 2) are aligned within the prescribed tolerance relating to length.

The present invention is not limited to the exemplary embodiments set forth hereinabove, and a person skilled in the art may easily make modifications to o the exemplary embodiments set forth hereinabove, within the technical scope encompassed by the claims.

REFERENCE SIGNS LIST

-   -   O: origin     -   1: plating device     -   2: plating fluid     -   3: plating tank     -   5: shaft-shaped member     -   5 c: center position of plated portion     -   5 l: length of plated portion     -   5 s: plated portion     -   6: rotary means     -   9: plating fluid spray nozzle     -   9 b, 9 f: plating fluid spray nozzle fasteners     -   10: positive electrode     -   10 b, 10 n, 10 f 1: shield fasteners     -   10 c: center position of output portion     -   10 l: length of output portion     -   10 f 2: metal cage fastener     -   10 m: shield     -   10 s: output portion     -   13, 15: shield jigs at either end     -   14: shield jig situated between shield jigs at either end     -   26: plating fluid spray orifices     -   26 c center position of plating fluid spray orifice     -   27 metal cage     -   28 metal pellets 

1. A plating device comprising a plating tank retaining a plating fluid, the device being used to carry out magnetic alloy plating of a shaft-shaped member immersed in the plating fluid, the shaft-shaped member serving as a negative electrode, wherein the plating device includes a plurality of shielding jigs fitted about an outer peripheral surface of the shaft-shaped member and defining a plated portion on the shaft-shaped member; and a positive electrode disposed surrounding the shaft-shaped member, and having an output portion facing the plated portion; characterized in that the center position of the plated portion and the center position of the output portion in the axial direction of the shaft-shaped member are aligned to within a predetermined tolerance relating to the center position.
 2. The plating device of claim 1, wherein a length of the plated portion and a length of the output portion of the positive electrode are aligned to within a predetermined tolerance relating to the length, in an axial direction of the shaft-shaped member.
 3. The plating device of claim 1, further comprising a shield disposed between the positive electrode and the shaft-shaped member.
 4. The plating device of claim 3, wherein a pattern of the shield defines a pattern of the output portion of the positive electrode, the pattern of the shield being determined such that variability of thickness of the magnetic alloy plating is kept to within an allowable range.
 5. The plating device of claim 3, wherein the shield is of assembly type detachable from the positive electrode.
 6. The plating device of claim 1, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
 7. The plating device of claim 6, wherein the center position of the plated portion and the center position of the plating fluid spray orifice are aligned to within an tolerance relating to the center position, in the axial direction of the shaft-shaped member.
 8. The plating device of claim 7, wherein the length of the plated portion and the length of the plating fluid spray orifice are aligned to within a prescribed tolerance relating to the length, in the axial direction of the shaft-shaped member.
 9. The plating device of claim 2, further comprising a shield disposed between the positive electrode and the shaft-shaped member.
 10. The plating device of claim 4, wherein the shield is of assembly type detachable from the positive electrode.
 11. The plating device of claim 2, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
 12. The plating device of claim 3, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
 13. The plating device of claim 4, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank.
 14. The plating device of claim 5, further comprising a plating fluid spray nozzle having a plating fluid spray orifice facing the plated portion, the plating fluid spray nozzle being of assembly type detachable from the plating tank. 